DESCRIPTION: Quinoenzymes are a widely distributed class of oxidoreductases with quinone cofactors that frequently occur with metal ions as part of catalytically functional redox active complexes. Metal- quinone complexes have also been implicated in the mechanism of action of pharmacologic agents, including antitumor antibiotics. The proposed project aims at the structural characterization and mechanistic elucidation of syntheticquinone-metal complexes designed as bioorganic models for understanding the mechanism of action of biologically active metal-quinone complexes. Through the use of optical spectroscopy, proton and 13C-NMR techniques as well as ESR methods, the structural and chemical properties of the complexes will be delineated. The redox chemistry will be developed using electrochemical methods as well as chemical reducing and oxidizing agents. The structural and chemical properties of semiquinone radicals and their metal complexes will be determined with these methods, and kinetic studies. The experiments outlined will focus on delineating the role of metal ions in influencing the reactivity of the redoxactive ligand including generation and characterization of the semiquinone intermediates. It will provide preliminary results toward the design of a more comprehensive research project on the structure and reactivity of p-quinone metal complexes.